Go-ahead for Ohma

J-Power are to begin construction of the Ohma nuclear power plant in May this year, now they have official authorisation for the boiling water reactor which is to run on a full-MOX fuel load.

Ohma's gestation

The Ohma project has developed slowly since J-Power first approached Ohma legislators in the late 1970s. At that time, it was hoped to build a 600 MWe demonstration unit based on the Advanced Thermal Reactor (ATR) that the Japan Atomic Energy Agency had been operating at Fugen.

In 1995 the ATR plan was scrapped and the ABWR (developed by GE, Hitachi and Toshiba) was chosen instead. An environmental impact assesment was submitted in 1998 and the licence application itself was made in 1999. This application was then withdrawn in 2004 so that the proposed plant layout could be amended, before a reapplication was made in the same year.

The application process was then slowed somewhat in 2005 by a query from Meti and a second public hearing. Finally, it was delayed again by extra considerations following the 16 July 2007 earthquake that affected the Kashiwazaki Kariwa nuclear power plant.

Authorisation for construction of the plant was granted on 23 April.

Authorisation for the reactor was granted today by the Ministry of Economy, Trade and Industry (Meti). J-Power hope the 1383 MWe Advanced Boiling Water Reactor (ABWR) will operate from March 2012. Site preparation has been underway since 2007.

J-Power's 2007 annual report said that it plans to use all mixed oxide (MOX) uranium and plutonium nuclear fuel in the reactor core which necessitates some design variation from the ABWR standard. Amendments for the different reactive and thermal properties of MOX fuel include a higher-capacity liquid control injection system; additional safety valves to release steam; control rods with enhanced neutron absorption; and automatic fuel inspection devices to reduce radiation exposure to workers.

Coal is the mainstay of J-Power's generation portfolio and Ohma is to be its first nuclear power project. The company said the low carbon dioxide emissions from nuclear power will help to lower its overall impact per unit of electricity delivered. It will be a "vital part in the establishment of a stable long-term business platform."

Currently, MOX fuel is produced for Japanese nuclear operators in France and the UK. In future, Japan Nuclear Fuel Ltd will operate a used nuclear fuel reprocessing and recycling complex at Rokkasho which will enable this to be done domestically. The completion of Rokkasho is currently slated for May this year. J-Power said that Ohma operating with a full MOX core would use 25% of Rokkasho's annual output. Another 15-17 reactors could use some amount of MOX by 2010 according to Japanese plans.